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Single-shot tomographic movies of evolving light-velocity objects.

Li Z, Zgadzaj R, Wang X, Chang YY, Downer MC - Nat Commun (2014)

Bottom Line: Tomography--cross-sectional imaging based on measuring radiation transmitted through an object along different directions--enables non-invasive imaging of hidden stationary objects, such as internal bodily organs, from their sequentially measured projections.Here we adapt tomographic methods to visualize--in one laser shot--the instantaneous structure and evolution of a laser-induced object propagating through a transparent Kerr medium.Our technique could potentially visualize, for example, plasma wakefield accelerators, optical rogue waves or fast ignitor pulses, light-velocity objects, whose detailed space-time dynamics are known only through intensive computer simulations.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, University of Texas at Austin, 1 University Station, C1600, 2512 Speedway, Austin, Texas 78712-1081, USA.

ABSTRACT
Tomography--cross-sectional imaging based on measuring radiation transmitted through an object along different directions--enables non-invasive imaging of hidden stationary objects, such as internal bodily organs, from their sequentially measured projections. Here we adapt tomographic methods to visualize--in one laser shot--the instantaneous structure and evolution of a laser-induced object propagating through a transparent Kerr medium. We reconstruct 'movies' of a laser pulse's diffraction, self-focusing and filamentation from phase 'streaks' imprinted onto probe pulses that cross the main pulse's path simultaneously at different angles. Multiple probes are generated and detected compactly and simply, making the system robust, easy to align and adaptable to many problems. Our technique could potentially visualize, for example, plasma wakefield accelerators, optical rogue waves or fast ignitor pulses, light-velocity objects, whose detailed space-time dynamics are known only through intensive computer simulations.

No MeSH data available.


Related in: MedlinePlus

Single-shot tomographic movies of the evolving index profile.(a) Selected 2D snapshots Δn(, xob) of the pump nonlinear index profile at five different propagation times tob indicated at the top and pump energies indicated at left. The horizontal axis of each snapshot is given in local position . The colour bar shows the dimensionless refractive index change. (b) Spectra of the transmitted pump pulses. The spectrum in the top row is nearly identical to the incident spectrum. (c) Near-field images of the transmitted pump spatial profiles, with a resolution of ~20 μm. Scale bar, 30 μm.
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f6: Single-shot tomographic movies of the evolving index profile.(a) Selected 2D snapshots Δn(, xob) of the pump nonlinear index profile at five different propagation times tob indicated at the top and pump energies indicated at left. The horizontal axis of each snapshot is given in local position . The colour bar shows the dimensionless refractive index change. (b) Spectra of the transmitted pump pulses. The spectrum in the top row is nearly identical to the incident spectrum. (c) Near-field images of the transmitted pump spatial profiles, with a resolution of ~20 μm. Scale bar, 30 μm.

Mentions: Figure 6a shows movie frames, or 2D snapshots, of the nonlinear index profile Δn(, xob) at five selected propagation times tob after entering (tob =0) and before exiting (tob =15 ps) the Kerr medium, for Epu from 0.4 μJ (top row) to 0.7 μJ (bottom row). The interframe spacing (Δtob=2.4 ps, Δzob=500 μm) approximates the interframe resolution limit for transverse profile variations and twice this limit for longitudinal variations. Supplementary Movie 1 shows continuously streaming movies with higher frame density. The main feature in each frame is a positive Δn(,xob) profile of transverse 1/e2 radius 13<Δxob<25 μm and longitudinal duration ~20 μm, or ~100 fs, that is attributable mainly to the instantaneous lowest-order nonlinear Kerr response n2Ipu of fused silica to the pump pulse. Diffraction, characterized by length =π(Δxob)2/λpun0(λpu), and self-focusing, characterized by focal length Lnl=λpu/2πn0n2Ipu (ref. 33), respectively, govern most transverse pump dynamics. The reconstruction resolves them as long as >500 μm (that is, Δxob>14 μm) and Lnl>500 μm (that is, Ipu<1 TW cm−2). Self-focusing beyond these limits can introduce dynamics faster than the interframe resolution, as well as additional nonlinearities such as plasma generation123435 and higher-order Kerr effect363738. Dispersion, characterized by length Ldis=/β2=277 mm, governs evolution of the longitudinal profile33. As Ldis≫L, the pulse and its n2Ipu profile propagate with negligible change in duration.


Single-shot tomographic movies of evolving light-velocity objects.

Li Z, Zgadzaj R, Wang X, Chang YY, Downer MC - Nat Commun (2014)

Single-shot tomographic movies of the evolving index profile.(a) Selected 2D snapshots Δn(, xob) of the pump nonlinear index profile at five different propagation times tob indicated at the top and pump energies indicated at left. The horizontal axis of each snapshot is given in local position . The colour bar shows the dimensionless refractive index change. (b) Spectra of the transmitted pump pulses. The spectrum in the top row is nearly identical to the incident spectrum. (c) Near-field images of the transmitted pump spatial profiles, with a resolution of ~20 μm. Scale bar, 30 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3921466&req=5

f6: Single-shot tomographic movies of the evolving index profile.(a) Selected 2D snapshots Δn(, xob) of the pump nonlinear index profile at five different propagation times tob indicated at the top and pump energies indicated at left. The horizontal axis of each snapshot is given in local position . The colour bar shows the dimensionless refractive index change. (b) Spectra of the transmitted pump pulses. The spectrum in the top row is nearly identical to the incident spectrum. (c) Near-field images of the transmitted pump spatial profiles, with a resolution of ~20 μm. Scale bar, 30 μm.
Mentions: Figure 6a shows movie frames, or 2D snapshots, of the nonlinear index profile Δn(, xob) at five selected propagation times tob after entering (tob =0) and before exiting (tob =15 ps) the Kerr medium, for Epu from 0.4 μJ (top row) to 0.7 μJ (bottom row). The interframe spacing (Δtob=2.4 ps, Δzob=500 μm) approximates the interframe resolution limit for transverse profile variations and twice this limit for longitudinal variations. Supplementary Movie 1 shows continuously streaming movies with higher frame density. The main feature in each frame is a positive Δn(,xob) profile of transverse 1/e2 radius 13<Δxob<25 μm and longitudinal duration ~20 μm, or ~100 fs, that is attributable mainly to the instantaneous lowest-order nonlinear Kerr response n2Ipu of fused silica to the pump pulse. Diffraction, characterized by length =π(Δxob)2/λpun0(λpu), and self-focusing, characterized by focal length Lnl=λpu/2πn0n2Ipu (ref. 33), respectively, govern most transverse pump dynamics. The reconstruction resolves them as long as >500 μm (that is, Δxob>14 μm) and Lnl>500 μm (that is, Ipu<1 TW cm−2). Self-focusing beyond these limits can introduce dynamics faster than the interframe resolution, as well as additional nonlinearities such as plasma generation123435 and higher-order Kerr effect363738. Dispersion, characterized by length Ldis=/β2=277 mm, governs evolution of the longitudinal profile33. As Ldis≫L, the pulse and its n2Ipu profile propagate with negligible change in duration.

Bottom Line: Tomography--cross-sectional imaging based on measuring radiation transmitted through an object along different directions--enables non-invasive imaging of hidden stationary objects, such as internal bodily organs, from their sequentially measured projections.Here we adapt tomographic methods to visualize--in one laser shot--the instantaneous structure and evolution of a laser-induced object propagating through a transparent Kerr medium.Our technique could potentially visualize, for example, plasma wakefield accelerators, optical rogue waves or fast ignitor pulses, light-velocity objects, whose detailed space-time dynamics are known only through intensive computer simulations.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, University of Texas at Austin, 1 University Station, C1600, 2512 Speedway, Austin, Texas 78712-1081, USA.

ABSTRACT
Tomography--cross-sectional imaging based on measuring radiation transmitted through an object along different directions--enables non-invasive imaging of hidden stationary objects, such as internal bodily organs, from their sequentially measured projections. Here we adapt tomographic methods to visualize--in one laser shot--the instantaneous structure and evolution of a laser-induced object propagating through a transparent Kerr medium. We reconstruct 'movies' of a laser pulse's diffraction, self-focusing and filamentation from phase 'streaks' imprinted onto probe pulses that cross the main pulse's path simultaneously at different angles. Multiple probes are generated and detected compactly and simply, making the system robust, easy to align and adaptable to many problems. Our technique could potentially visualize, for example, plasma wakefield accelerators, optical rogue waves or fast ignitor pulses, light-velocity objects, whose detailed space-time dynamics are known only through intensive computer simulations.

No MeSH data available.


Related in: MedlinePlus